Has anyone replaced a submergible pump themselfs?

I didn't have water this morning. Everything was fine last night (filled the horse trough, etc), but this morning all I had was what was in the pressure tank. Check circuit breaker and that was fine. I haven't had time to check any further (had to get to work). I'm hoping that its the pressure switch or something simple but figure at worst its the pump. I will probably have a "professional" do the job unless I find out that its fairly straight forward job.

Larry