Blitting images onto a tile that is part of a grid in pygame

First of all, t he code which defines and loads the images, can be simplified a lot:

il = ['image' + str(i) + '.bmp' for i in range(1,9)]
pygame_image_surfaces = [pygame.image.load(os.path.join(path, name)) for name in imagenames]

The image which is associated to a Tile is stored in the instance attribute self.content of the Tile object. Use this attribute to draw the tile:

class Tile:

    # [...]

    def draw_content(self):
        image_rect = self.content.get_rect(center = self.rect.center)
        Tile.surface.blit(self.content, image_rect)

    def draw(self):
        # draw the contents of a tile to its surface. 
        #  - self: the tile being drawn
        self.draw_content()
        pygame.draw.rect(Tile.surface, Tile.fg_color, self.rect, Tile.border_width) 

    def set_content(self, new_content):
        #   - self: the tile whose content is being updated
        self.content = new_content

Create 1 random list of images. And use this list to set the images for the entire grid of tiles:

class Game:

    # [...]

    def create_grid(self, grid_size):
        # Creates a grid of tiles that is grid_size x grid_size in size.

        imgnames = ['image' + str(i) + '.bmp' for i in range(1,9)]
        image_surfaces = [pygame.image.load(os.path.join(path, name)) for name in imgnames]
        image_surfaces = image_surfaces + image_surfaces
        random.shuffle(image_surfaces)

        self.grid = []
        # this for loop creates each row in our grid  
        for row_num in range(grid_size):
            new_row = self.create_row(row_num, grid_size, image_surfaces)
            self.grid.append(new_row)

    def create_row(self, row_num, size, images):
        # Create one row in a grid. Each row contains size Tiles.
        # required for calculating the tile's x,y coordinates on screen
        #  -  row_num: the nth row of the grid being created
        #  -   size  : the number of tiles in the row 
        # returns the newly created row'

        tile_height = self.surface.get_height() // size
        tile_width = 3/4*self.surface.get_width() // size
        new_row = []
        for col_num in range(size):
              pos = (row_num * tile_height + 10, col_num * tile_width + 10)
              content = images[row_num*size + col_num]
              one_tile = Tile(pos, tile_width, tile_height)
              one_tile.set_content(content)
              new_row.append(one_tile)
        return new_row