WP All Import provides a number of options for sideloading images to the posts it creates. Watch the video below for an overview of a few different ways to import images.
When creating a new import, you can specify the settings for importing your images in Step 3. To add images to an existing import, go to Manage Imports -> Edit Import.
For each record in your file, WP All Import will create a post, import the images associated with that record to the post’s Media Gallery, and optionally set the Featured Image.