Puppies do have a need to chew, especially when they are teething. But they must be taught what is appropriate for them to chew on, and what is not. Be sure to supply your puppy with appropriate things, like puppy rawhide, rubber balls, ropes, etc., making sure they are things that won't break off into small objects, where they can choke to death on them. Besides teething many puppies bite us for another reason, they want to be the alpha dog. Biting is one of several behaviors related to dominance.
Puppies start early determining their future status in the pack.
Since the pack leaders, are alphas and the alphas, get the best of everything, it is only natural that puppies will want to become the Alpha Dog. When the pups mother teaches the bite inhibition to her pup, she will let the puppy know that what he is doing hurts by a yelp, the next time she may try yelping. If the puppy doesn't back off to these warnings, she will, growl rather fiercely, grab him by the neck and will pin him to the ground. If the pup doesn't submit, to her, she will increase her jaw pressure until he does. So when your puppy bites, try yelping and push him away or walk away.