How to use terraform import with module
The terraform import command uses the "Resource Address" syntax, which is a way to talk about objects in a configuration from outside of that configuration. (This is as opposed to references in the main Terraform language, which are always resolved in the context of a particular module.)

To refer to a resource that is declared in a child module, you can add a module path to the beginning of the address:

terraform import module.assets.aws_s3_bucket.machine-learning BUCKET-NAME