2 ways I would try to approach this:
1) Put the picture from the db onto the clipboard, then use Word's ability to paste to add the picture.
(Might make users really mad to have their clipboard manipulated though. It would make me mad...)
2) Write the picture out to a file, then use word's ability to insert the contents of a file into a document.
Doing this directly seems kind of hard; Word doesn't really give you direct access to the .doc, so as to be able to directly add the picture.