Within the worldwide network of ambassadors, there resides a pride of pianists whose music-making is both avocation and relaxation from arduous political responsibilities. Egidio Ortona, warmly remembered for his years of distinction as Italy's ambassador to this country, was a pianist of note.So is Adrien Meisch, the Luxembourg ambassador to the United States.

On Saturday night, the audience in the Kennedy Center's Terrace Theater was introduced to still another musical ambassador, Jaime Ingram, who is Panama's ambassador to Spain. Ingram and his wife, Nelly, played a recital of two-piano music that was distinguished by the Second Suite of Rachmaninoff and the great sonata that Francis Poulenc wrote for American pianists Arthur Gold and Robert Fizdale.

The concert was the first in a new series planned jointly by the Organization of American States and the Kennedy Center. The Ingram's playing has the kind of assured ensemble that can only be attained through long hours of work. The music emerged as if guided by a single mind communicating through four hands on two pianos.

There were felicitous touches in phrasing, beautiful gradations in rhythmic impulse and a lovely quality of tone that took on special beauty when the Ingrams moved into the fragrance of Octavio Pinto's "Scenas Infantis" and a seductive Romance by Carlos Guastavino. Greater subtleties in light and shadow are possible in both the Rachmaninoff and Poulenc than the Ingrams found, but it may be scaled down in the intimacy of the Terrace Theater. Their encores, a Bach "Siciliana" and the Lutoslawski-Paganini Variations, contained some of the evening's most persuasive playing.