The four Salvadoran rebel leaders who will resume peace negotiations with government representatives Friday arrived here tonight professing hopes that some useful result would come out of their second round of peace talks.

"We have come here with all our willingness to make another step forward in the long process for achieving justice and liberty for our people," said Ruben Zamora, a leader of the Farabundo Marti National Liberation Front and its political arm, the Democratic Revolutionary Front. He and two other representatives to the talks flew into the San Salvador International Airport with a foreign diplomatic escort on a chartered Mexican plane.

The fourth representative, guerrilla leader Facundo Guardado, was driven into the capital under escort of the Swiss ambassador and the International Red Cross today from a guerrilla base in northern Chalatenango province.

All four rebel leaders spent the night at the walled residence of the Spanish ambassador. They were to drive early Friday to the Salesian seminary at Ayagualo, nine miles south of the capital, for a day's talks with four negotiators selected by President Jose Napoleon Duarte.

The possibility of a cease-fire has caused unease within the Army ever since Duarte initiated the peace talks. In the past two weeks, Army commanders have met three times to discuss the peace talks and to raise their objections to certain aspects of them.

Meanwhile, in a meeting with high-ranking officers yesterday, Duarte, in his capacity as commander in chief, won the officers' approval to dismiss a lieutenant who has been accused of masterminding the slaying of two U.S. AFL-CIO advisers and a Salvadoran official, government sources said.

Lt. Isidro Lopez Sibrian, has been accused of masterminding the killing of Michael Hammer and Mark Pearlman, and the Salvadoran land reform chief, Jose Rodolfo Viera, on Jan. 3, 198l.

Efforts to have Lopez Sibrian tried failed, and 10 days ago the Salvadoran Supreme Court refused to accept a government request to reopen the case.