I have done 8 quite long treks with one or other of my guides - two brothers, one per trek.
The first 5 treks they were engaged and paid directly by me (ie no agency was involved). My main guide, the elder of the two, either arranged his/his brother's personal insurance through an agency he also did work for, or directly with the Lumbini Insurance Company (LIC). For one trek all 3 of us went into LIC's offices whilst the insurance was arranged - the documents were of course all in Nepali (which I don't speak, let alone read). But my main guide said it was the insurer that the good agencies used, and that other guides had used for their private work. It was my main guide who made me aware of the legal, and practical, need for trekking staff to have good insurance - there is no social security in Nepal. They have always been very careful re their insurance. I arrange my own insurance in the UK before I leave for Nepal.
For our 3 most recent treks, 2014-16, due to changes in the rules or their enforcement, we have trekked on blue TIMS cards which can only be issued by an agency - blue TIMS cards are now required for anyone trekking with staff. This means that the agency is responsible for providing insurance for "their" staff - I still engaged and paid my guides directly. Both my guides would be checking that they agency, which they know, would arrange good insurance (some agencies may not, whatever the rules say...).
So you could pass on the suggestion of the Lumbini Insurance Company. Karl Edvard has lots of experience, so perhaps see what arrangements he makes. It will be much more difficult if you meet the person outside Ktm, but Nepalis are good at finding proper solutions to problems such as this. Uninsured staff would be a moral (and legal) risk, in my view.
