From looking at it, that on-edge style threading insert is somewhat generic between different manufacturers. You may want to look through some different suppliers to see if you can find other sources for the carbide.
At my job I have some internal threading bars that use that style insert, but all the inserts we have for it are 3/16" wide (4.76mm) and they're all ground to cut a thread with that minimum pitch. (5 thread per inch or ~4.75mm metric pitch). It wouldn't surprise me if the inserts were available in smaller forms, although I can't speak to it myself.