The Hugo documentation have a nice example on how to structure images and other resources in a page bundle.
The basic idea is to store all the content for a page in a folder where the main content is inside index.md.
A sample structure for this page.
└── content
└── post
└── 2018-03-02-hello-page-bundle
├── index.md // <- https://example.com/post/018-03-02-hello-page-bundle/
└── hello_my_name_is.jpg // <- https://example.com/post/018-03-02-hello-page-bundle/hello_my_name_is.jpg
It is also possible to leave the main content page outside the bundle. This is the actual structure used.
└── content
└── post
├── 2018-03-02-hello-page-bundle.md // <- https://example.com/post/018-03-02-hello-page-bundle/
└── 2018-03-02-hello-page-bundle
└── hello_my_name_is.jpg // <- https://example.com/post/018-03-02-hello-page-bundle/hello_my_name_is.jpg
And finally the bundled image.