It's a puppy thing! Best thing to do is to provide lots of things to chew on.....and when she is caught chewing on the wrong thing, a sharp "no" with a chew toy given to her. When she starts to chew on a chew toy, she should be told "good girl". If your friend consistently redirects, she will catch on. Tell her the best thing to do is to keep it positive...no yelling!
I use Nylabones...but only the durable ones that are not digestible. I also use Bitter Apple spray as another poster suggested.
0h, and when they are into that chewing stage it is wise to keep them crated when they cannot be closely observed! They can end up chewing something hazarous to them.