I can't tell if that is fireblight, but very generally speaking, when you prune a pear tree, you don't want to see ANY brown-stained areas in the cut. If you do, sterilize the pruner blades -- I use alcohol in an atomizer spray, some people dip in 10%? chlorine bleach water. THEN cut several inches further down the same branch and check for any brown. Repeat, if necessary until you get to healthy, cream- colored cross-section with healthy green sub-bark layer.
Burn or securely bag and trash the affected branches.
...oooh Jona posted while I was composing my message... JONA, if you are still here, please check my content and point out if this is incorrect.