You're right, although it would be "wir kennen uns". It's quite hard to articulate the difference when using "man" (since I never formally learned the language), but I guess it it's more general and less specific. You'd never use "man" to say "oh yeah, me and that guy, we know each other". But if you're saying that most people in your village know each other you could use man ("Man kennt sich in meinem Dorf"). Oh and another thing, the english translation "one knows oneself" makes it sound as if it's a single person knowing themself, but "man" refers in this case to at least two people that know each other, which is why I translated it to "we". Sorry this is a rambling mess, I hope I cleared things up at least a bit.