这个翻译不太好，因为可能会产生歧义，前面用walking修饰three people,强调了三个人走路的状态，那么find sth to learn 可能会误读为从走路的三人那里学到的一些东西，可以指走路的姿势，如何保持距离等，而汉语所表达的含义完全不是这样。请看我在维基词典和外刊找到的更为准确的译文：
When I walk along with two others, they may serve me as my teachers. （维基词典提供的译文）
When three men are walking, one is bound to be my teacher. (外刊）
If three men are walking together, one of them is bound to be good enough to be my teacher. （外刊）
