@ucornes: I know this problem pretty well.. Moreover I think that, 'Copy,paste and stitch' method is the only one working if You are dealing with different mesh densities (part and insert meshes).
@nordhb: I have followed this topic. In my cases CADDOC is not a really helpful tool. But I will try that method with something smaller one day.
Regarding improvement in MF12 - I can totally agree. I have compared results from MF11 and MF12, and for non-precise contact, MF12 is not showing 'funny' temperature distribution. Of course in MF13 is also so.