Users looking for azw to mp3 conversion are usually looking for a way to convert digital book to audio book, i.e. conversion of Amazon Kindle ebooks to MP3 audio.
The most reliably way to do this, would be to use some text-to-speech converter, such as Balabolka, that will generate audio file (.mp3) from text source (.azw). Usually uses the voices provided by Microsoft, but some programs have their own unique ones.