To answer your question, no Wells Fargo cannot pursue your other property. They can only reclaim title to the property that has secured the debt. However, dependent upon the nature of the debt, you may be liable to pay back any "non-purchase money" loans... these include any refinances or home equity lines of credits. The website Steve provided below explains the difference between debt incurred to purchase a property and debt incurred either to refinance or pull money out of the property. However, it does not mention the Mortgage Foregiveness Debt Relief Act of 2007 passed by George Bush at the onset of the current housing downturn. This bill provides for the exclusion of taxation on any debt foregiveness.
Check out this website to learn more about this bill and if it applies to your situation (you may have to copy and paste into your browser):
I hope that is additionally helpful to you.
Best of luck.... and know that you are not alone.
San Diego Real Estate Specialist
Residential Sales and Appraisal