Unfortunately, you didn't tell about the audio source... Does it come from the CDs.. or it comes from whatever like iTunes Store (means : Already compressed)...
If the file was already compressed, then it's no use to convert it into a WAV.. but if you RIP the CD into the WAV, then it makes a different story...
I suggest you try both of them... before makin' the video, and compare about the audio quality (just trust your ears)... if the MP3 is more than enough, then just go with the MP3... cause it also gives you less space than the WAV (Uncompressed)
And, the audio quality of your files will always be the same with the result of your video then... except, if you manage to re-convert the mp3 again... So using the WAV as a source Audio is a good idea, than it's up to you to choose between the MP3 & WAV as the Audio Result in your WMF...
And mostly people won't notice the difference between the 'higher' bitrate of MP3 & a WAV file... but some people might notice it (an expert audio user, audiophile )...