If the old tile is in good shape and still holding securely to the wall, you may be able to avoid the cost and labor of tearing it out and replacing it or adding an insert. Check your yellow pages for porcelain (spelling?) refinishers. The same folks who can refinish a bathtup or sink can do ceramic tile. The finish is sprayed on, and a good job can last for years. My cousin had it done three years ago in his only tub/shower and it still looks great.