In Pamplona you can find good wine from Navarra, try it! it's really good. You can order it in every bar as "tinto" red wine or as "clarete" or "rosado" rose wine. Besides there's a liquor called "Patxaran", made with wild berries and anisette, that should be tried.
You should also make sure you try the Sangria. It's a red wine punch, usually with some fruit, red wine, and some honey to sweeten. The alcoholic content can vary greatly from place to place.
Calle San Nicolas, Calle San Antón, Calle Estafeta, Calle NavarrerÃa and Calle de Jarauta are all lined with different bars, pubs, and bodegas. Most do not have signs so feel free to wander around in and out of these places. And if you see a good bunch of locals enjoying their "pintxos" it is usually a good sign!