Solicitor General Charles Fried, whose office rarely shows much turnover at the top, unveiled high-level changes yesterday in his office, which represents the federal government in cases before the Supreme Court.

Fried announced new appointments for three of the five deputy slots in his office: Donald B. Ayer, now U.S. attorney in Sacramento, will become counselor to Fried; Washington lawyer Louis R. Cohen will handle antitrust and regulatory matters, and William Bryson, former head of the Justice Department's criminal division, will take over criminal cases for the solicitor's office.

Three veterans in the office said yesterday that they are leaving to join the 20 lawyers in the D.C. office of Mayer, Brown & Platt, a Chicago-based firm of more than 300 lawyers. They are Deputy Solicitor General Andrew L. Frey, a 14-year veteran who handled criminal cases; Kenneth S. Geller, a 10-year veteran who oversaw civil litigation, and senior assistant solicitor general Kathryn Oberly, a 12-year veteran.

No Place Like Home . . . Senate Majority Leader Robert J. Dole (R-Kan.) has decided not to accept the resignation of staffer Brent Bahler, who outraged Kansas constituents a few weeks back with an extemporaneous travelogue that described Dole's home state as "a wasteland." His remarks, describing a drive through Kansas, were made in the presence of several reporters in Topeka.

According to Mike Pettit, Dole's administrative assistant, the senator decided to accept Bahler's apology and his explanation that his words were intended as humor. "Suffice it to say," Pettit said, "he understands now it was not the least bit funny."

Contra-Indications . . . Bosco Matamoros, the Washington spokesman for the largest Nicaraguan rebel group, the Nicaraguan Democratic Force (FDN), is -- depending on who you talk to -- being replaced, moved aside or bolstered in his efforts to woo the U.S. news media.

The rebel umbrella group, the United Nicaraguan Opposition (UNO), is bringing in its own voice, Carlos Ulvert, who is described by one State Department official as "an effort to clean up the act over there."

By all reports, Ulvert is articulate, urbane and U.S.-educated, while Matamoros openly hankers to be back in Italy where he was schooled. Matamoros said he expects "to cooperate fully" with the new UNO flak.

Fersh Among Equals . . . Robert J. Fersh, staff director of the House Agriculture nutrition subcommittee for the past three years, is leaving to become executive director of the Food Research and Action Center, a nonprofit organization that works on hunger and nutrition problems of the poor. Rep. Leon E. Panetta (D-Calif.), subcommittee chairman, has not yet chosen a successor to Fersh. The subcommittee has jurisdiction over the food-stamp program and federal surplus-food distribution program.