Water pumps were a weak point on the earlier Traverse, Enclave, and Acadia models (Saturn Outlook also) My new at the time 2010 went bad after only 2 years. GM extended the warranty on them for 10 years/120000 miles BUT I think only through the 2010 model year. Check with a dealer to find out for sure and read Post#2 of this link for more information. GM Extended Water Pump Warranty
You can change it going through the wheel well if I recall. Just check some of the Traverse/Enclave/Acadia forums for more information.