Former West German Chancellor Willy Brandt today named 16 persons - four of them former heads of government - who will join him on a commission to seek ways to reconcile the potentially explosive differences between the wealthier northern part of the world and the poorer south.

Brandt, 64, who was asked to head the commission earlier this year by World Bank President Robert McNamara, has long held the view that the gap between the developing countries and those already industrialized is the key issue confronting the world.

"The traditional structures of worldwide politics are subject to profound change. East-West rlations are increasingly overwhelmed by growing tensions between north and south," he said in an interview last year.

Brandt, who is chairman of West Germany's ruling Social Democatic Party, will try to act as a broker between the two worlds in his new partime job.

The commission, he told a press conference here, probably will meet four times over the next year and produce a report in 18 months that might serve as a guide to improved relations.

The four former government leaders on the commission are Britain's Edward Heath, France's Pierre Mendes-France, Sweden's Olof Palme and Chile's Eduardo Frei.

The commission, supported by voluntary contributions, is to work independently of governments. Brandt named the Netherlands as one country that had already made a sizeable donation.

Nine of the panel's 16 members are from the so-called developing states. None is from the Soviet bloc. Bonn has often made a point that the Soviet bloc does not do enough to aid developing countries and that West Germany alone provides twice as much such aid as Moscow and its allies.

Yet Brandt seemed to suggest today that he had no illusions about how difficult it would be to reach consensus even without the Soviet bloc represented. Therefor he did not seek them out. Others doubted that the Warsaw Pact countries would have joined anyway. Many of the Third World countries are Marxist dominated.

Brandt will meet in Moscow next month with Soviet President Leonid Brezhnev, it was announced today and there has been speculation for months that Bradt would discuss with the Soviets some form of relations with the commission.

The two American representatives are former Commerce Secretary Peter G. Peterson and Washington Post publisher Katherine Graham.

Others include: Abdullatif Y. Hamed of Kuwait, Rodrigo Botero Montoya of Colombia, Antoine Kipsa Dakoure of Upper Volta, Amir H. Jamal of Tanzania, Laksmi Kant Jha of India, Adam Malik of Indonesia, Joe Morris of Canada, Shridath S. Ramphal of Guyana, Nobuhilo Ushiba of Japan, and Layachi Yaker of Algeria.