After any batch import, click Download URL Mapping CSV. You'll get a spreadsheet that pairs each original web URL with its new location in your Media Library, listed as Old URL → New URL.
This is especially handy when replacing externally hosted images: run a find-and-replace in your database using the mapping file, and every old image link across your posts updates to point at your local Media Library copy.
Note: Only users with permission to upload media can download the mapping file. Partial mapping files are cleaned up automatically if an import is canceled.