It's quite possible that this was already requested, but I cannot find such a task.
Visual Editor has an Insert -> Template function. I couldn't find a way to insert an invocation of a Scribunto Lua module the same way, even though modules are quite similar to templates.
I guess that the reason for this is that there is an assumption that modules are usually not used directly in articles, but are only used internally in templates. I suspect, however, that this assumption is not quite true: searching the main space of the English Wikipedia for insource:#invoke finds quite a lot of direct module invocations.
It appears to be possible to edit a module that was included just like editing a template. Its name will appear as "#invoke:Module name". I couldn't find a way to insert a new one, however, and it should be possible.
I actually have very little experience with developing Scribunto Lua modules, so I might be very wrong about this, but as far as I can see, a module invocation is not very different from a template, except the #invoke: part, and also passing the Lua function name as the first parameter. So I guess that the dialog for inserting a function can look almost the same as the one for inserting a template. Perhaps it can even be the same dialog, an if the user asks for a module, it will add another input box that asks for the function name.
Another issue is that I'm not aware of a way for a Lua module to list the parameters in a structured way that is similar to TemplateData, and perhaps it should be added.