teething is not a reason to go exclusively pumping. my boy just started growing his first two teeth a month ago and i continued latching him on at home and pumping only when i am at work.
when my boy bit me from time to time during nursing, i will say a very sharp and firm 'No!' and look sternly at him. if he continued, i would unlatch him, (sometimes even prop him up to sit but he was old enough to sit unsupported already) and glare at him so that he knew I was not pleased with his biting. every time he bit me, i would do the same actions again and again. after a few times, he learnt his lesson - that he would not get any milk if he was naughty.
to help your baby with his teething, what you can do is to chill his teether and give to him to bite for some time before you latch him on. the chilled teether would have helped to numb his gums so that when he is latched on, he doesn't feel so much the urge to bite you. give it a try! =>