$file_image='/var/www/html/drupal/sites/default/files/2017-04/images.jpeg';

$file_content = file_get_contents($file_image);

$directory = 'public://Image/';

file_prepare_directory($directory, FILE_CREATE_DIRECTORY);

$file_image = file_save_data($file_content, $directory . basename($file_image),     FILE_EXISTS_REPLACE);

$user = User::create([

       'name' =>'user',

       'mail' => 'user@gmail.com',

        'pass' => 'password',

        'status' => 1,

        'roles' => array('editor','administrator'),

        'user_picture' => array('target_id' =>$file_image->id()),

        'timezone'=> 'Indian/Christmas'

      ]);

$user->save();