A Washington man convicted last month of first-degree murder after a jury rejected his insanity defense was sentenced yesterday to 23 years to life in prison.

Michael Wood, a 32-year-old prison parolee who for years had been shuttled between St. Elizabeths Hospital and Lorton Reformatory by officials who disagreed over his mental condition, had contended he was insane when he shot John R. Bowman during an apparent robbery attempt June 2, 1979.

Wood's attorney, Robert Pleshaw, yesterday asked D.C. Superior Court Judge George H. Revercomb to consider his client's "long history of mental problems" and trial testimony by defense psychiatrists that he was "substantially ill at the time of the killing."

Assistant U.S. Attorney Barry M. Tapp said in court that Wood had been faking mental illness for years to avoid prosecution on various crimes and that "the jury saw through Michael Wood's veil of insanity."

Revercomb said that testimony by psychiatrists created "a very substantial question of (Wood's) mental state from time to time, but not necessarily at the time the offense was committed."

Revercomb sentenced Wood to a minimum of 20 years for the murder conviction, two to 15 years for attempted robbery while armed and three to 10 years for carrying a pistol without a license. The latter sentence is to run consecutive to the other two, which Wood will serve concurrently.