I have a pair of Mavic wheels with worn out rims which are one of the CXP (CXP21 model, I think) which I've been meaning to break down. Would they have the inserts? They have a 36/36 spoke count, so definitely enough for your requirements.
OK well it's bad news I'm afraid as it turned out that the wheels I told you about that I believed were a set actually weren't, and so only one of the wheels was a CXP model. Unfortunately, the second one had a v profile, was the same colour, and was mavic, so hence my thinking both were the CXP model and would match. The non CXP wheel doesn't have the inserts. One of them was CXP (CXP33) model, but naturally you want two wheel's worth of the inserts, so I'm sure there'd be no point in your messing around with only half of what you need. The inserts also look slightly different to the ones in your pics above, but I suppose could essentially be the same thing.