Hello,
Neu Werbas is today a part of Vrbas. Try to contact: Dajc Franja, Kulski Put 33, 21460 Vrbas, Serbia Tel. 021/708-139 who would probably know old families with German names. Apparently, according to my friend from Vrbas there was a Fritz Zepp there 30 years ago, with a large family, he was born in mid 1930-ies. He traded with horses. Possible address Danila Bojovica 31 or 33, 21460 Vrbas, Serbia.
Good luck!
Cheers,
Marta Balan