If you can't get Edit to embed an image/button component, there's always another trick.
Take a Panel, turn off its border and in the OnPaint event paint it like Edit — just use ThemeServices. Then take Edit, turn off its border and embed it in the panel. Next to Edit, place the component with the image (button or whatever you like) and also embed it in the panel.
And that's it — everything looks like it should and has appropriate margins, thanks to which the image will not cover the text. In this way you can embed what you need and where you need.