The phrase "well-of" is typically used to describe someone who is very knowledgeable or skilled in a particular area. Some synonyms for this phrase include "expert," "authority," "guru," "master," "specialist," and "aficionado." These words all suggest a high level of competence and understanding in a particular field. Other related terms that could be used to describe a well-of person might include "scholar," "savant," "pro," or "virtuoso." Regardless of the specific term used, the idea is to convey a sense of deep knowledge and understanding in a particular subject matter.