This problem can be solved by adding the relevant sitemap images (at least the navigational) as web resources and setting the image url to the web resource.
I have shown how this can be done below.
For this to work out you need to add the image as a web resource and should give the name pwks_Mngt to it. You can give any name you want. Then the image is distributed with the solution and you will not have any issues finding the image file.