Images not displaying after importing pages in wordpress

Hi
I recently redesigned a website from Divi to GeneratePress. Clients asked me to design thing from scratch. Now we are facing traffic down issues. While redesigning we have around 2500 images on new site. But there are more than 4000 images on our backup site (Original Divi Cloned Site). Clients is thinking this could be the reason for traffic down. He asked me to upload all new designed pages and posts on our Old Backup site. I deleted all posts and pages on Old Site and then used the WordPress Import plugin to Import all pages/posts from new designed site on Old Backup site. Now all pages are on imported but not showing any image on any page or post page. Remember all images are available on Media Library with same name. Is there any method/ trick so images will show automatically on all new imported pages/posts. I want to save time, otherwise I will have to select each image manually on each page/post page. Kindly hide links of the sites.

Humble Regards