This worked for me when I tried it on a mp3 file.
$ ffmpeg -i somefile.mp3 -f segment -segment_time 3 -c copy out%03d.mp3 Where -segment_time is the amount of time you want per each file (in seconds).
References
Splitting an audio file into chunks of a specified length 4.22 segment, stream_segment, ssegment - ffmpeg documentation