Ugh!! I found that smetimes the pump was quite harsh... some things to help- lanolin on it, perhaps some breast milk on it, and check that your pump is the right size- can you get different sized ..um.. what are they clled.... the bit that goes on your boob.. You can get different ones with the madela...
Is it manual? Can you perhaps switch to a manual pump so you have more control over the pressure? How bad is the abrasion? And do you mean that you don't BF from that side?