The family name is known in today Poland, but it is a seldom family-name. It is known in two forms: Umperowicz (ten people, mostly in west part of Poland) and Umpirowicz (34 people, mostly in west and north parts of Poland). The name is derived form the personal name of German origin Humbert (hun 'the name of the Huns' tribe' + beraht 'bright, hell') with the Suffix -owicz and means 'the son of Humbert'. The name Humbert was adapted into the Polish language as Umber, Umper or Umpir and from these forms were family names derived. All the forms you are giving are the variations of the same family name. These variations are the result of adaptation of the family name to German or other languages, so you write Umperovitch and you read [Umperovicz] (cz as in English chair). Writing as -vitch, witz are the results of adaptations of the family name into German, where the names with Polish -icz, -owicz were so written.
I've only heard this name on the character Humbert Humbert from Lolita, and I can definitely understand why this name hasn't been used since. This name will always be associated with that story, because that story is old, and it has clearly stood the test of time, as people still read it, and there will surely be more movies made of it. Plus, sexually premature girls will surely be called Lolitas for a long time to come, which is another reason why the story sticks around. Besides, this is a very old-fashioned, rather geeky, and somewhat elitist name.