There is nothing wrong with sharing .wma files, but the majority of users steer clear of .wma meaning not many will upload them from you

Converting wma to mp3 is not a good idea either because there will be a drop in quality.

It is best to convert directly from lossless audio, high bitrate .wav (700+ kbps) or .flac which is a lossless format to mp3 and using high bitrate (at least 192 kbps. 256 or even 320 recommended)

Majority of users doing this will not bother getting to technical and just rip the CD directly to 320 kbps mp3 as even Windows Media Player can do this. Not the best way but still a 320 kbps rip like this is still better than a well converted CD into 192 kbps

Hope this sheds some light on the subject