Most of my best friends are Newars so I can say I know a thing or two about Newars. There are many different castes and sub-castes within the newar community which were mostly based on their profession when the cast system was made. For example: Chitrakaar was used for people who were painters by profession. Similarly, JYAPU represented the FARMERS of the newar community. Hence, JYAPU is one of the many communities inside the Newars. So to call all newars JYAPU only shows that one has so limited knowledge about that community. And personally, I don't think that JYAPU word itself carries any derogatory meaning. What's wrong with being a farmer? It's only an another profession.