Sooner or later, you are going to find yourself in a job where there is somebody you can't get along with. It could be a colleague, a subordinate or--all the worse for you--your boss.

Take, for example, the abrasive manager who prods his beleaguered staff with bulldozer tactics. Impatient with everyone, he or she rules through intimidation.

Or the office know-it-all at the next desk, who--everyone quickly discovers--has little of consequence to say. Nevertheless, this co-worker feels compelled to have the last word in every exchange. To keep the peace, you grin and bear it.

Maybe it's the wet blanket on your staff who, no matter what is proposed, can be counted on to respond: "It's never going to work."

And who can ignore the walking time bomb? The office mate who periodically explodes, rendering everyone within earshot into embarrassed silence.

Who can blame you for thinking how much more pleasant the atmosphere would be--and how much easier your job--if only you could get these people to change. Think again, says energy and management consultant Robert E. Mumford Jr., a former Navy captain who teaches an Open University workshop on "handling difficult people."

In most cases, "You are not going to change that person," says Mumford, 46, a former LST (tank landing ship) commander who taught "human resources management" to future commanding officers.

"What it gets down to is that you've got to change your own behavior. If you want change," he says, "you change, and the other person will react differently."

The people who show up for his workshop find the concept often "difficult to get across emotionally, although they can understand it intellectually.".

"When people come," he says, "they usually have a specific person in mind." He hastens to inform them on what he considers an underlying principle of his class: "People are not fundamentally evil. If you can break the code, you can find a way of effectively dealing with them."

If, for example, your boss is a bulldozer, "The only way . . . is to stand up to the intimidation. You can't wilt under the pressure." Easier, of course, said than done, but Mumford suggests you have a better chance if you practice your response.

A woman friend--who had a difficult boss--was given a raise she felt was too small, but she was too frightened to ask for more.

"So I spent a Sunday playing her boss. I was the most obnoxious, overbearing person. We practiced 25 times. She cried. She laughed. But finally, no matter what I did, she knew what to say."

On Monday, wrapped in her new courage, she argued her case and got the raise. But afterward, because the tension had been so great, "She threw up."

Much of the disagreement between you and a co-worker may be based simply on misunderstanding, says Mumford. "You hear people described as being 'arrogant.' That's another way of saying 'self-confident,' or 'ambitious' or 'assertive.' "

Perhaps you are the kind of person who asks a lot of "why" questions. For example, "Why did you do it that way?" To many people, "that almost always means 'I don't agree with what you did.'"

Maybe you are the kind of person who sends "you" messages. They often cause hostility, he says. Instead of "Can't you keep it a little more quiet," he suggests an "I" message: "I've got an important report to finish here, and I'm having a little trouble concentrating."

Eventually, says Mumford, workshop participants begin to realize that they may share much of the responsibility for tension. "We try to get to that point gently."

For those who can get to that point, Mumford suggests:

* Taking the "empty know-it-all" aside and saying, " 'I've found different information.' Do it assertively, but let them save face. They'll minimize that behavior around you."

* Remembering that with a "nay-saying wet-blanket," there is almost always "an element of truth in what they are saying." They could be once-eager bureaucrats whose proposals have been shot down often. Acknowledge what they are saying, advises Mumford, but add, "I think we've got a different approach. I think we can pull it off."

* Realizing that tantrum-throwers probably rely on this technique because it has worked for them before. "They've gotten what they wanted, and it has been reinforced . . . Let them run down. Or I stand up and put up my hand like a stop sign in a non-threatening way. They usually will stop."

A final caution if your deskmate is driving you crazy:

"Everyone is difficult to somebody."

"Handling Difficult People" is scheduled for March 18 and 25, 7-9:30 p.m., Chevy Chase Presbyterian Church. Fee: $20. Phone Open University, 966-9606.