Functions that are only there some of the time can have a shortcut made while you are in the right state. For example, select just a face that has a texture, then go into Preferences, Shortcuts, and search for Position. You will then see the ‘flyout’ menu option for texture position, and can assign the key you want.
I’m not sure what Insert Texture is, but if you mean import, you could set a shortcut for File/Import, but would still have to manually select the file, and make sure it’s set to import as a texture.